Journal Article

Characterization of the Major Histocompatibility Complex Class II Binding Site on LAG-3 Protein

Prigent, Philippe, Maigret, Bernard, El-Tayar, Nabil, Dréano, Michel, Triebel, Frédéric, Bruniquel, Denis, Huard, Bertrand, Donini, Silvia, Mastrangeli, Renato

1997

Overview

The lymphocyte activation gene-3 (LAG-3), selectively transcribed in human activated T and NK cells, encodes a ligand for major histocompatibility complex (MHC) class II molecules. Like CD4, LAG-3 ectodomain is composed of four Ig-like domains (D1-D4). Nothing is known about the LAG-3 regions or residues required to form a stable MHC class II binding site. In contrast to CD4, soluble LAG-3 molecules stably interact with MHC class II molecules expressed on the cell surface. In addition, the first two N-terminal domains of soluble LAG-3 (D1 and D2) molecules, alone, are capable of binding MHC class II. From a LAG-3 model structure, we designed mutants and tested their ability to bind MHC class II molecules in an intercellular adhesion assay. We found residues on the membrane-distal, CDR1-2-containing top face of D1 that are essential for either binding or repulsing MHC class II proteins. Most of these residues are clustered at the base of a large extra-loop structure that is a hallmark of the LAG-3 D1 Ig-like domain. In addition, as for CD4, oligomerization of LAG-3 on the cell surface may be required to form a stable MHC binding site because mutation of three residues in the ABED β -strands containing side of D1 results in a dominant negative effect (i.e., binding inhibition of coexpressed wild-type LAG-3).

• Publisher: National Academy of Sciences of the United States of America,National Acad Sciences,The National Academy of Sciences of the USA
• Subject: Amino Acid Sequence / Amino acids / Animals / Antibodies, Monoclonal / Antigens, CD - chemistry / B lymphocytes / Binding Sites / Biological Sciences / CD4 Antigens - chemistry / COS Cells / Genetic mutation / Histocompatibility Antigens Class II - chemistry / Histocompatibility Antigens Class II - metabolism / HLA-D Antigens - chemistry / HLA-D Antigens - metabolism / Humans / Killer Cells, Natural - immunology / Kinetics / Ligands / Lymphocyte Activation / Lymphocyte Activation Gene 3 Protein / Membrane Proteins - biosynthesis / Membrane Proteins - chemistry / Membrane Proteins - metabolism / Models, Molecular / Models, Structural / Molecular interactions / Molecular Sequence Data / Molecules / Mutagenesis, Site-Directed / Point Mutation / Proteins / Recombinant Proteins - biosynthesis / Recombinant Proteins - chemistry / Recombinant Proteins - metabolism / Sequence Homology, Amino Acid / T lymphocytes / T-Lymphocytes - immunology / Transfection / Tumor Cells, Cultured